CN104846400B - A kind of electrolysis device based on electrowetting principle on dielectric layer and preparation method thereof - Google Patents

Abstract

The invention discloses a kind of electrolysis device based on electrowetting principle on dielectric layer and preparation method thereof, the electrolysis device is included：Bottom crown, it is set gradually constituted from top to bottom by the first substrate, electrode layer, dielectric layer, the first hydrophobic layer；And, top crown, it is set gradually constituted from top to bottom by the second substrate, grounding electrode and the second hydrophobic layer；Drop D to be electrolysed is placed between the first hydrophobic layer and the second hydrophobic layer；The electrode layer includes some electrolysis electrodes and some driving electrodes, electrode electrical isolation between any two；Electrolysis electrode insertion is arranged in driving electrodes.The present invention obtains the drop containing certain concentration opposed polarity electrolysate by the control to electrolytic process and drop breakup process.The electrolysis device that the present invention is provided has the features such as novel in design, control is simple, automaticity is high, output accuracy is high, is greatly expanded the application of the technologies such as digital microcurrent-controlled and field quick detection.

Description

An electrolytic device based on the principle of electrowetting on a dielectric layer and its preparation method

technical field

The invention belongs to the technical field of digital microfluidics, and relates to a microfluidic technology based on the principle of electrowetting on a medium layer and an electrolysis process of a liquid, in particular to an electrolytic device based on the principle of electrowetting on a medium layer.

Background technique

Lab-on-a-chip can be simply defined as a miniaturized and integrated micro-electro-mechanical system that can complete various processes of biochemical processing and automatically complete traditional laboratory functions. Its goal is to integrate a complete analysis process on a single device, with high integration High-precision, high-precision, low-consumption, intelligent and other advantages, it has very good prospects in many fields such as biology and chemistry.

As the power part of lab-on-a-chip, microfluidic technology plays an important role. The electrowetting technology on the medium changes the wettability of the droplet on the surface of the medium by voltage to control the droplet. It has many advantages such as simple driving method, strong driving force, and high degree of automation, but it has disadvantages such as single function and low integration. .

Electrolysis is a commonly used technology in many fields such as biology and chemistry, but most of the existing electrolysis methods have problems such as bubble generation, uneven distribution of electrolysis products, inaccurate control of the degree of electrolysis reaction, strict process conditions, and large amount of reagents. It limits its application in fields such as portable equipment and lab-on-a-chip. Therefore, it is of great significance to realize the integration of electrolysis function in the digital microfluidic chip.

Contents of the invention

The purpose of the present invention is to provide an integrated digital microfluidic chip that can accurately generate quantitative electrolytic products and divide the oxidized products and reduced products into different droplets, and is compatible with the existing microfluidic technology. Expand the application range of digital microfluidic technology on the basis of improving the existing electrolytic functional devices.

To achieve the above object, the present invention provides an electrolytic device based on the principle of electrowetting on a dielectric layer, the electrolytic device comprising:

a lower pole plate, the lower pole plate is composed of a first substrate, an electrode layer, a dielectric layer, and a first hydrophobic layer arranged in sequence from bottom to top; and

An upper plate, the upper plate is composed of a second substrate, a ground electrode and a second hydrophobic layer arranged in sequence from top to bottom;

The electrolytic liquid drop D is placed between the first hydrophobic layer and the second hydrophobic layer; wherein, the electrode layer includes several electrolytic electrodes and several driving electrodes, and the electrodes are electrically isolated between two electrodes; the electrolytic electrodes are embedded in the In the driving electrode, the electrolysis function is integrated into the digital microfluidic device, and the isolation of the electrolysis product can be realized. The "embedding" of the electrolysis electrodes means that the electrolysis electrodes are surrounded but electrically isolated by the driving electrodes of the digital microfluidic chip, and the electrodes are on the same plane.

The shape, size and "embedded" position of the driving electrode and the electrolysis electrode are not strictly limited, and the design criterion is to realize its function, but the size of the electrolysis electrode should be as small as possible under the condition that the electrolysis function can be realized, and can be driven by the electrode. Surrounded so that the droplets can be transported and electrolyzed by the electrolysis electrodes, and there is no liquid residue on the electrodes when the droplets are transported away.

The "droplet" to be electrolyzed refers to the droplet that can be used for electrowetting on the dielectric layer, and its composition is not limited, it can be a single biological sample, or it can be composed of multiple components; at the same time, its size is not limited , considering the limitations of the droplet-driven structure, it is best to be between picoliters and several milliliters.

The above electrolysis device, wherein the electrolysis electrodes are composed of electrolysis anode E _p and electrolysis cathode E _n , and are separated by several driving electrodes.

The electrolysis device above, wherein the electrolysis anode E _p and the electrolysis cathode _En are exposed and can be in direct contact with the droplet D to be electrolyzed. The electrolysis electrode is not covered with the dielectric layer and the hydrophobic layer, and the liquid droplets are transported to the electrolysis electrode through the digital microflow automatic control method to realize automatic electrolysis and droplet splitting to enhance the working efficiency of the electrolysis electrode.

In the above electrolysis device, the electrolysis electrodes and the driving electrodes are planar electrodes.

In the above electrolysis device, the upper and lower surfaces of the electrolysis electrode and the driving electrode are on the same plane.

In the above electrolytic device, the first substrate and the second substrate are made of insulating materials.

The above-mentioned electrolytic device, wherein, the material of the dielectric layer is a non-conductive substance with a certain dielectric constant and breakdown resistance, preferably a substance with a high dielectric constant and strong breakdown resistance, including but not limited to alicyclic epoxy Resin CEP, SU-8, tantalum pentoxide, etc.

In the above-mentioned electrolytic device, the materials of the first hydrophobic layer and the second hydrophobic layer are selected to reduce the surface tension of the droplet, including but not limited to Teflon, Cytop, and the like.

The present invention also provides a method for preparing an electrolytic device based on the principle of electrowetting on a dielectric layer, the method comprising:

Step 1, preparing the lower plate: preparing an electrode layer including several driving electrodes and electrolytic electrodes on the first substrate, wherein the electrolytic electrodes are embedded in the driving electrodes; preparing a dielectric layer on the electrode layer; preparing a first electrode layer on the dielectric layer Hydrophobic layer, and make the electrolysis electrode exposed to the medium layer and the first hydrophobic layer;

Step 2, preparing the upper plate: preparing a ground electrode on the second substrate, and then preparing a second hydrophobic layer;

Step 3, assembling the upper plate and the lower plate to form the electrolytic device based on the principle of electrowetting on the dielectric layer.

Based on the principle of electrowetting on the dielectric layer, the present invention proposes a new type of microfluidic device that integrates the electrolysis function into the structure of the digital microfluidic chip. Processes such as droplet splitting and electrolysis operate on droplets to generate droplets containing different electrolysis products.

The electrolytic integrated digital microfluidic chip based on the principle of electrowetting on the dielectric layer provided by the present invention has the following advantages:

a) The electrolytic electrode is integrated into the driving electrode of the digital microfluidic chip, which simplifies the chip structure and simplifies the manufacturing process.

b) The droplet transportation and electrolysis process can be fully automated, fast, and high throughput, which is conducive to the rapid generation of a large number of droplets containing electrolysis products, and realizes precise control of the concentration of electrolysis products inside the droplets.

c) The electrolytic electrode only occupies a small part of the chip, which is conducive to the integration of more functions and the portable application of the chip, and expands the application range of the digital microfluidic chip.

Description of drawings

Fig. 1 is a structural schematic view (longitudinal sectional view) of an electrolytic device based on the principle of electrowetting on a dielectric layer according to the present invention.

Fig. 2 is a schematic diagram of the electrode configuration of the lower plate of the electrolytic device based on the principle of electrowetting on the dielectric layer according to the present invention.

detailed description

The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present invention, and are not intended to limit the protection scope of the present invention.

The electrolytic device based on the principle of electrowetting on the dielectric layer provided by the present invention is realized through electrode design and driving signal control, so it can be configured in various ways and can be configured in various digital microfluidic chips.

The schematic structural diagram (longitudinal section view) of the present invention is shown in FIG. 1 . On the insulating first substrate 100 are the driving electrodes E1-E6 and the electrolysis electrodes Ep and En of the present invention, wherein the electrolysis electrodes Ep and En are respectively embedded in the driving electrodes E3 and E5, but are electrically isolated from each other. The material used as the substrate is not fixed, as long as it is insulated; the electrolysis electrode material should be a metal that meets the electrolysis requirements, and the digital micro-flow driving electrode (including the upper plate electrode, that is, the ground electrode 105) can be made of any conductive material in principle. Composition of materials, but in order to simplify the chip manufacturing process, it is preferably the same material as the electrolysis electrodes; the size, interval and number of all electrodes are not limited, this specification only takes a certain number and specifications of electrodes as an example; the drawings at the end of the article are only The schematic diagram does not accurately reflect the position and arrangement of the electrodes.

A dielectric layer 102 is provided on the electrodes, and a hydrophobic layer 103 is provided thereon. The first substrate 100 , the electrode layer 101 , the dielectric layer 102 and the first hydrophobic layer 103 together constitute the lower plate 201 of the device. The driven droplet D is placed on the lower plate 201 , the second hydrophobic layer 104 is placed on the droplet, the ground electrode 105 is on the second hydrophobic layer 104 , and the insulating second substrate 106 is on the second hydrophobic layer 104 . The material of the ground electrode 105 is not limited, but in order to expand the integration of chip functions, it is preferably a conductive transparent material, such as indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), and the like. The second hydrophobic layer 104 , the ground electrode 105 and the second substrate 106 together constitute the upper plate 202 of the device.

In the present invention, the electrolysis electrodes must be exposed so that the solution can contact the electrolysis electrodes for electrolysis, that is, the 102 dielectric layer and the 103 hydrophobic layer above the electrolysis electrodes must be removed. In actual preparation, photolithography or mechanical methods can be used to remove the two layers of materials at the same time, or the dielectric layer 102 on the electrolytic electrode can be removed before the hydrophobic layer 103 is prepared, and then photolithography or stripping (lift- off) and other methods to remove the hydrophobic layer 103 on the electrolysis electrode. In the present invention, the droplet D between the upper and lower plates can be driven by applying a voltage control signal to the drive electrode and the ground electrode is grounded, and the electrolysis operation can be performed by drawing out the electrolysis electrodes En and Ep.

The schematic diagram of the electrode configuration principle of the present invention is shown in Figure 2. The electrolytic cathode and electrolytic anode (E _n , E _p ) are respectively embedded in the spaced driving electrodes of the electrowetting structure on the traditional dielectric layer, and these five electrodes cooperate to complete the liquid Droplet splitting, electrolysis and isolation of electrolysis products. The liquid droplets are carried on the electrodes E1-E3 through the transport process. At this time, the three driving electrodes are all applied with effective driving voltages, and then the electrolysis voltages with opposite electrical properties are applied to the electrolysis electrodes En and Ep to electrolyze the liquid. When the electrolysis After the process is completed, the electrode E2 is grounded to break the liquid from the middle to form two droplets containing the reduced product and the oxidized product respectively. It should be pointed out that the above is only a schematic illustration of the present invention, and it is allowed to improve and expand the structure and application of the device without affecting its functionality.

In the present invention, the voltage application (power-on) of the drive electrodes refers to that the voltage of the corresponding electrodes is set to be non-zero when the chip implements droplet manipulation, so that the electrowetting drive can occur.

In the present invention, the voltage application (power-on) of the electrolysis electrodes refers to that the voltage corresponding to the electrolysis electrodes is set to be non-zero when the chip implements droplet manipulation so that the electrolysis process can occur.

In the present invention, the "grounding" means that the voltage of the corresponding electrode is set to 0 or sufficiently close to 0 when the chip implements droplet manipulation.

With reference to Fig. 1 and Fig. 2, a possible preparation process of the electrolytic integrated digital microfluidic chip of the present invention is as follows:

Step 1, forming a metal film on the lower plate insulation first substrate 100 by spin coating, evaporation, sputtering and other processes, and forming a driving electrode and an integrated electrolytic electrode by photolithography;

In step 2, an insulating dielectric layer is prepared by methods such as spin coating, physical sputtering, and chemical vapor deposition, and a "pit" on the integrated electrochemical electrode is formed by photolithography to expose the electrolytic electrode. It should be pointed out that if the material of the dielectric layer is a special material such as SU-8, the required structure can be formed by one-step photolithography film formation method;

Step 3, preparing a hydrophobic layer by methods such as spin coating, evaporation, and sputtering to form a film, and removing the surface of the electrolytic electrode by photolithography. In addition, the lift off process (lift off) can be used, that is, the photolithographic pattern is first formed, and then the hydrophobic layer is formed, and then the unnecessary part is removed by the lift off method, and the insulating dielectric layer and the hydrophobic layer can not be photolithographically etched during the film preparation process. etch to expose the electrolytic electrodes by mechanical means after preparation;

Step 4, the upper plate is formed on the insulating second substrate 106 by spin coating, evaporation, sputtering and other processes to form a metal film to form the ground electrode 105, and then the second hydrophobic layer 104 is prepared by spin coating, sputtering and other methods;

Step 5, assembling the upper plate and the lower plate to form a digital microfluidic chip. Since then, the preparation of the novel electrolytic device based on the principle of electrowetting on the dielectric layer of the present invention has been completed. After combining it with other microfluidic devices, the digital microfluidic operation method can be used to automatically realize various operations and operations of the solution. sensing.

The core original point of this application is that the exposed electrodes are used for liquid electrolysis, and combined with the EWOD (electrowetting-on-dielectrics, electrowetting on medium) droplet generation process to achieve the isolation of electrolysis products. Specifically, the driving electrode of the electrolytic device provided by the present invention is covered with an insulating medium layer and a hydrophobic layer, and the dielectric layer and the hydrophobic layer above the electrolytic electrode are removed so that the electrolytic electrode is "bare"; The electrowetting principle on the layer is transported to the top of the integrated electrolysis electrode through the driving electrode, and it contacts the electrolysis electrode for electrolysis, and the generated liquid droplets containing electrolysis products are then transported away from the electrolysis electrode, thereby realizing automatic control.

The electrolysis device of the present invention is also suitable for applications where isolation of the electrolysis product is not required, in which case only the electrolysis process is performed and no droplet splitting operation is performed.

Although the content of the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as limiting the present invention. Various modifications and alterations to the present invention will become apparent to those skilled in the art upon reading the above disclosure. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims (7)

1. a kind of electrolysis device based on electrowetting principle on dielectric layer, it is characterised in that the electrolysis device is included：

Bottom crown (201), the bottom crown (201) is by the first substrate (100), electrode layer (101), dielectric layer (102), first hydrophobic Layer (103) sets gradually composition from top to bottom；And

Top crown (202), the top crown (202) by the second substrate (106), grounding electrode (105) and the second hydrophobic layer (104) from Top to bottm sets gradually composition；

Drop (D) to be electrolysed is placed between the first hydrophobic layer (103) and the second hydrophobic layer (104)；Wherein, described electrode layer (101) some electrolysis electrodes and some driving electrodes, electrode electrical isolation between any two are included；The electrolysis electrode insertion is set In driving electrodes；Described electrolysis electrode is by electrolytic anode (E_p) and electrolysis cathode (E_n) composition, and by some driving electrodes every Open；Electrolytic anode (the E_p) and electrolysis cathode (E_n) exposed setting, can directly it be contacted with drop to be electrolysed (D).

2. device is electrolysed as claimed in claim 1, it is characterised in that described electrolysis electrode and driving electrodes is plane electricity Pole.

3. device is electrolysed as claimed in claim 2, it is characterised in that described electrolysis electrode and the upper and lower surface of driving electrodes It is in same plane.

4. electrolysis device as claimed in claim 1, it is characterised in that described the first substrate (100), the second substrate (106) Using insulating materials.

5. device is electrolysed as claimed in claim 1, it is characterised in that described dielectric layer (102) is high dielectric constant material, Any one in CEP, SU-8 and tantalum pentoxide.

6. electrolysis device as claimed in claim 1, it is characterised in that described the first hydrophobic layer (103), the second hydrophobic layer (104) it is hydrophobic material, selected from fluororesin.

7. a kind of preparation method based on the electrolysis device of electrowetting principle on dielectric layer, it is characterised in that this method is included：

Step 1, bottom crown (201) is prepared：The electrode comprising some driving electrodes and electrolysis electrode is prepared in the first substrate (100) Layer (101), wherein, electrolysis electrode is embedded in driving electrodes；Dielectric layer (102) is prepared on electrode layer (101)；In dielectric layer (102) the first hydrophobic layer (103) is prepared on, and causes electrolysis electrode to be exposed to dielectric layer (102) and the first hydrophobic layer (103)；

Step 2, top crown (202) is prepared：Grounding electrode (105) is prepared on the second substrate (106), then prepares the second hydrophobic layer (104)；

Step 3, top crown, bottom crown are assembled to form the described electrolysis device based on electrowetting principle on dielectric layer.